1. Field of the Invention
This invention relates to a magnetic recording/reproducing apparatus and an electric apparatus, and more particularly to a magnetic recording/reproducing apparatus and an electric apparatus which are simple in structure and capable of reducing their production cost.
2. Description of the Related Art
Conventionally, a magnetic tape apparatus such as a video cassette recorder is known as an example of magnetic recording/reproducing apparatus or an electric apparatus. The magnetic tape apparatus is provided with a pair of reels for forwardly and inversely rotating a pair of tape reels on a tape supply side and a tape take-up side, which are accommodated in a tape cassette. In order to change the rotating direction of the reels, an idler mechanism is employed. A structure of the idler mechanism is known in which an idler gear attached to a swing arm is displaced to swing between a first position where rotation is transmitted to the one reel and a second position where the rotation is transmitted to the other reel.
In such an idler mechanism, in order to swing the idler gear between the first position and the second position, a rotating torque (swinging torque) which exerts on the swing arm must be generated. Conventionally, in order to generate such the swinging torque, for example, a spring is arranged so as to press the idler gear toward the swing arm.
As a mechanism for generating the swinging torque without using such a spring, an idler mechanism as disclosed in Japanese Utility Model Registration No. 3086328 (FIGS. 1 and 2) has been proposed. FIG. 9 is a schematic view of the main part of a magnetic tape apparatus which adopts the conventional idler mechanism disclosed in Japanese Utility Model Registration No. 3086328. FIG. 10 is a schematic partially broken enlarged side view of the idler mechanism taken along line X—X in FIG. 9. Now referring to FIGS. 9 and 10, the idler mechanism of the conventional magnetic tape apparatus will be described briefly.
As shown in FIGS. 9 and 10, the conventional idler mechanism includes a pair of reels 181, 182 for rotating tape reels of a tape cassette, gears 183, 184 which are concentrically attached to the reels 181, 182, respectively, a train of gears 185 and an idler mechanism 106. The train of two gears 185 are in mesh with a gear 184.
The idler mechanism 106 includes an input gear 162, a swing arm 164 rotatably connected to one end of a center axis 163 of the input gear, and an idler gear 161 in mesh with the input gear 162 in an area 170 (see FIG. 10). The center axis 163 is rotatably fit in a hole 165 of the swing arm 164. The idler gear 161 has a bearing hole 167 formed at the central portion (FIG. 10). In the bearing hole 167 of the idler gear 161, a shaft portion 166 (FIG. 10) which is formed to protrude at the end of the swing arm 164 is inserted. The idler gear 161 is rotatable about the shaft portion 166. The input gear 162 has a flange integrally formed. The flange 168 has a slanting side face 169. At a single position (concretely, below the area 170 where the input gear 162 and idler gear 161 are in mesh with each other), the side face 169 and the idler gear 161 are in contact with each other.
In the idler mechanism shown in FIGS. 9 and 10, since the idler gear 161 is in contact with the side face 169 of the flange 168 of the input gear 162, when the input gear 162 rotates, because of the friction resistance generated at the contact area, the rotating torque for moving the idler gear 161 is generated. Specifically, by changing the rotating direction of the input gear 162, switching can be made between the state where the reel 181 is rotated by the idler gear 161 and the state where the reel 182 is rotated by the idler gear 161 (the swing arm 164 can be displaced to swing about the center axis 163).
However, the conventional idler mechanism described above presents the following problem. Specifically, the idler mechanism in which the spring is arranged to press the idler gear on the swing arm has a complicated structure and requires an increased number of components because of the spring as a separate component. Therefore, the production cost of the magnetic tape apparatus is increased.
In the idler mechanism shown in FIGS. 9 and 10, although the separate member such as a spring is not employed, the input gear 162 having a specific shape equipped with the flange 168 is employed. Therefore, the production cost of the input gear 162 having the specific shape may become higher than that of a usual gear. As a result, the production cost of the entire magnetic tape apparatus cannot be reduced sufficiently.